Signal leakage is a common problem for high density radio frequency (RF) connectors that are mounted to printed circuit boards (PCB). Therefore, isolation of any signal leakage from one signal port to another is an important requirement in electronic systems. The most difficult area to prevent leakage or cross talk is the junction between the PCB and the connector. That issue is amplified at the interface between the connector and the PCB when the connector is an all metal construction, which is typically done to improve signal isolation within the connector itself. There is often a small air gap left between the connector body and the PCB after installation. This gap is a significant leakage area. Most commonly, RF connectors are soldered to the PCB with an improved geometry to fence off one signal line from another to manage the leakage area. Typically this improved geometry included fully soldered surface mount barriers between adjacent lines. However, multi-port connector also tend to be larger with a larger thermal mass. Soldering of a connector with large mass can be difficult, problematic, or even impossible. The preferred method to attach large mass connectors is press fit type to allow effective connection without soldering. With press-fit RF connectors, the solutions for suppressing signal leakage are limited. One technique is to increase the number of ground contacts to create a fence to limit leakage at each port. However, that is not effective for very tight isolation specifications because a fence always allows some amount of leakage at the PCB launch. Another technique is to fit a compressible conductive EMI suppression gasket between the RF connector and the PCB. However, that technique introduces risk when additional factors, such as warpage of the connector or the PCB, as well as thermal cycles, which leads to compression set in the gasket, thereby significantly degrading signal isolation.
Another solution has been to add a metal component, such as a shim, between the RF connector and the PCB interface. The shim includes an array of holes that correspond to the high density ports of the RF connector. However, the holes still allow some signal leakage, which can be significant if one or more of the holes is offset due to a manufacturing issue and as such is misaligned with the ports of the connector. To address any leakage from the holes, one solution has been to use a cone shaped solid shield for each port for fitting into the respective holes of the shim. However, such a solid shield does not provide enough mechanical flexibility to address misalignment and varying tolerances in the shim holes, which would result in short term and long term reliability concerns. In the short term, if the cones are not sufficiently aligned with the holes, they will not result in a 360 degree contact joint and will therefore leak RF inconsistently. In the long term, there is a concern that the contact force between the cone and the hole will diminish. The contact in this case has minimal spring qualities to ensure the connection can be maintained over long periods with various environmental factors such as temperature vibration and shock. The contact joint being simply an interference fit between the cone and hole with soft materials to allow deformation. These materials can creep or permanently deform over time with temperature fluctuation and other mechanical stresses.
Therefore, a need exists for a high density RF connector that mounts to a PCB and maximizes signal isolation.